Over the past several years, natural gas wells have been drilled in geographic areas where the gas producing geological formation has a very low permeability. These geological structures release natural gas very slowly, and are commonly called tight formations. Typically, such tight formations are deep in the earth, and hence drilling a well is expensive. Because the natural gas flows so slowly, the normal production techniques utilizing a pipeline network are not feasible for tight formation gas wells; the amount of natural gas that can be recovered over a reasonable period of time is insufficient to justify the capital and operating expenditures required for production.
The natural gas reserves represented by tight formation areas are very large, however, and thus these wells are valuable and important. Basins containing tight formations stretch through Louisana and Texas, and north through the northern Great Plains into Canada. In the United States alone, the reserves of natural gas in such tight formation areas are believed to be more than 400 Tcf. Beyond this, similar geological areas can be found world-wide.
Because of the huge volume of natural gas available in tight formation areas and the continuing need for energy, considerable research has been and is being conducted seeking ways to increase the rate of production from tight formation wells. One technique has been to employ massive hydraulic fracturing, which has proven to be effective in some instances. This technique is expensive, however, and adequate results are not assured. In the late 1960's and early 1970's nuclear devices were also utilized in efforts to increase natural gas flow, but did not produce good results. Other similar techniques are currently under development.
All of the techniques thus far proposed to increase the yield from tight formation areas share the characteristic of being expensive to implement, with the chances for success problematical. The typical gas well in a tight formation area is deep and thus is difficult to work with, and in addition the formations producing the natural gas may be several in number and vertically separated. Despite the large investment already made in attempting to economically produce tight formation gas wells through techniques designed to increase the release of natural gas from the formation, progress has been slow and results have been less than promising. Because of this the vast natural gas reserves available in these fields remains largely untapped.
There is thus a serious need for a new methods and apparatus for producing tight formation gas wells in an economical manner, avoiding the difficulties thus far encountered and making it practical to utilize the natural gas from these wells to meet the energy requirements of the world. The present invention is intended to satisfy that need.